Rigging Fundamentals
Sling types, hardware selection, hitch configurations, sling angle effects, capacity ratings, and rigging inspection requirements.
- Identify common sling types and their appropriate applications
- Explain shackle, hook, and hardware selection and inspection criteria
- Calculate sling angle effects on capacity
- Describe proper tag line use and load control methods
Lección 1
Sling Types & Hitch Configurations
Common Sling Types
Rigging connects the crane hook to the load. The choice of sling type depends on the load characteristics, weight, environmental conditions, and lift requirements. Every sling has a rated capacity that must exceed the forces it will experience during the lift.
Wire Rope Slings
Construction: Steel wire rope with eyes or fittings
Best for: Heavy loads, high temperatures
Caution: Can damage load surface, requires inspection for broken wires
Synthetic Web Slings
Construction: Nylon or polyester webbing
Best for: Finished surfaces, moderate loads
Caution: Damaged by heat, chemicals, UV exposure, sharp edges
Chain Slings
Construction: Alloy steel chain links
Best for: Extreme heat, rough loads, permanent rigging
Caution: Heavy, can scratch surfaces, must check for stretch/wear
Hitch Configurations
The way a sling is attached to the load significantly affects its rated capacity:
| Hitch Type | Capacity Factor | Description |
|---|---|---|
| Vertical hitch | 100% of rated capacity | Single leg, straight vertical pull |
| Choker hitch | 75% of rated capacity | Sling wrapped around load and through eye |
| Basket hitch | 200% of rated capacity | Both ends on hook, load cradled (at 90 degrees) |
Basket Hitch Angle Effect
A basket hitch only provides 200% capacity when the sling legs are vertical (90 degrees to horizontal). As the angle decreases, the capacity decreases. At 60 degrees, capacity drops to approximately 173%. At 45 degrees, it drops to approximately 141%.
Sling Selection Factors
When selecting slings for a lift, consider:
- Load weight and distribution
- Number of sling legs
- Sling angles
- Environmental conditions (temperature, chemicals)
- Load surface protection requirements
- Required working load limit with safety factor
ASME B30.5-2021 Qualified Rigger Mandate
ASME B30.5-2021 introduced a significant expansion of the qualified rigger requirement for mobile crane operations. A qualified rigger must be employed for any mobile crane lift where the load exceeds 2,000 lbs, regardless of whether personnel are in proximity, in the fall zone, or involved in assembly/disassembly activities.
This broadens the scope considerably from earlier interpretations that limited the qualified rigger requirement to personnel hoisting and assembly/disassembly. The 2,000 lb threshold applies to the total suspended load including rigging weight.
2,000 lb Threshold - No Exceptions for Proximity
ASME B30.5-2021 requires a qualified rigger for any mobile crane lift exceeding 2,000 lbs. This mandate is not limited to lifts near personnel or special operations. If the total suspended load including rigging exceeds 2,000 lbs, a qualified rigger must be involved.
Sling types include wire rope, synthetic web, and chain - each suited to different applications. Hitch configuration dramatically affects capacity: vertical hitch uses full rating, choker hitch reduces to 75%, and basket hitch can double the capacity at 90 degrees. Always match sling selection to load requirements. Per ASME B30.5-2021, a qualified rigger is required for any mobile crane lift exceeding 2,000 lbs - this applies regardless of personnel proximity.